Falsifiability is a fundamental property of a statement of it being possible to have counter-examples to (the search for these counter-examples is called falsification). According to Karl Popper, claims that are not falsifiable are considered to be outside the realm of science. This criterion is accepted by most of the worldwide scientific community. If the theory a unfalsifiable, the burden of proof that the theory is incorrect cannot lie on a skeptic.
- Main Article: Russell's Teapot
When considering unfalsifiable claims, Bertrand Russell used an analogy of a celestial teapot. If a teapot was drifting in space between the Earth and Mars (making it unobservable), he claimed it would be unreasonable to expect belief of the teapot based on their inability to disprove the teapots existence. He compared the belief in God to the belief in a celestial teapot; in both cases it is not the responsibility of disbelievers to disprove its existence.
"[Y]ou could claim that anything's real if the only basis for believing in it is that nobody's proved it doesn't exist!"
Special creation is not falsifiable. There is no test which could show, even theoretically, that things were not specially created if they weren't. There is also no test which could show God didn't hire unicorns to create us if he didn't. It is also conceivable that the universe was created last Thursday with the appearance of great age. Without falsifiability there are an infinite number of alternatives one can't prove, all of which have equal merit. Other concepts that are unfalsifiable include: Omphalism, the dragon in my garage and God of the gaps.
The existence of God or Gods is unfalsifiable. Gods may exist in an inaccessible spiritual world or be immune from testing. "It is said: 'Do not put the Lord your God to the test." Luke 4:12 For this reason, the burden of proof for the existence of God lays on believers and not with skeptics.
The Theory of Evolution is falsifiable.  Had the fossil record been found to be static, it would have shown that species have not evolved. Had a mechanism been found that prevents, and has always prevented, genetic mutations from accumulating or being inherited, it would make evolution impossible. However, the opposite is true in both cases - those things were instead found to support the theory. Another possible disproof of evolution would be species spontaneously appearing without any likely ancestors. This would be observed in the fossil record as "out of place" species, such as a "precambrian rabbit".
Christianity is the most falsifiable religion
- "The central claims of the Bible demand historic inquiry, as they are based on public events that can be historically verified. In contrast, the central claims of all other religions cannot be historically tested and, therefore, are beyond falsifiability or inquiry. [...] The amazing thing about Christianity is that there is so much historic data to be tested. "
If it were falsifiable, apologists could give specific examples of exactly how it can be falsified today. However, they have failed to do so and rely on the lack of refutation in the Bible itself.
The apologists give little in the way of evidence apart from the Biblical account of the life, death and resurrection of Jesus. The "facts" that Jesus had a public ministry, was executed publicly and was witnessed by many are merely claims in the Bible, which itself is not necessarily true. The Gospels were written many decades after the events they describe. It would be all to easy to ignore any critics or doubters when the Gospels were compiled.
Other religions are based on easily refutable recent history, such as John Frum of the cargo cults. This shows that people can take historic events, adopt some strange interpretation of their significance and form a religion. Being falsifiable does not automatically imply truth.
Science is not falsifiable
- "Because science by definition is a "theory" - not testable, observable nor repeatable, why do you object to creationism or intelligent design being taught in school?"
The definition of science used by the apologist is the inverse of the correct definition! The most likely explanation is that the writer was mislead to believe that evolution is not falsifiable, and then confused evolution with all of science.
- Harry Potter and the Deathly Hallows, Google Books
- J.K. Rowling quotations at goodreads.com
- Talk origins archive, Claim CA211
- Matt Stopera, 22 Messages From Creationists To People Who Believe In Evolution, Buzzfeed, February 5, 2014